The present invention relates to liquid products for washing dishes in a customary domestic dishwashing machine. In particular, the invention relates to nonaqueous liquid dishwashing products for machine dishwashing.
Machine dishwasher products for household use are usually supplied in the form of powders or more recently also in the form of shaped bodies (tablets). The supply form of a liquid in this sector has hitherto only achieved minor importance on the market. Compared with the solid supply forms, liquids do, however, have advantages with regard to dosing and esthetic product advantages which should not be underestimated, which make this supply form of interest. For example, there is already broad prior art both with regard to nonaqueous, for the most part solvent-based, but also with regard to aqueous dishwashing products for washing dishes in a customary domestic dishwashing machine.
For example, DE 20 29 598 describes liquid cleaning compositions which comprise 14 to 35% by weight of sodium tripolyphosphate, 0.1 to 50% by weight of a potassium and/or ammonium salt of an inorganic or organic acid, water, and optionally surfactants, solubility promoters, sequestrants, persalts and other ingredients.
Linear-viscoelastic cleaning compositions for machine dishwashing are also described in European patent application EP 446 761 (Colgate). The compositions disclosed here comprise up to 2% by weight of a long-chain fatty acid or a salt thereof, 0.1 to 5% by weight of surfactant, 5 to 40% by weight of water-soluble builders, and up to 20% by weight of chlorine bleaches and a polycarboxylate thickener, where the ratio of potassium ions to sodium ions in these compositions should be 1:1 to 45:1.
Machine dishwasher products in the form of clear, transparent gels are disclosed in European patent application EP 439 878 (Union Camp Corp.). The compositions described therein comprise a polyacrylate thickener, which forms a gel matrix with water, surfactant, bleach, a builder and water.
Machine dishwasher products in the form of gels are also described in European patent application EP 611 206 (Colgate). These compositions comprise 1 to 12% by weight of a liquid nonionic surfactant, 2 to 70% by weight of builders, and enzymes and a stabilization system which is composed of swelling substances and hydroxypropylcellulose.
Viscoelastic, thixotropic dishwashing products comprising 0.001 to 5% by weight of surfactant, and enzymes and an enzyme stabilization system of boric acid and polyhydroxy compounds are described in international patent application WO 93/21299 (Procter & Gamble). The products disclosed therein likewise comprise 0.1 to 10% by weight of one or more thickeners.
Dishes washed by machine are nowadays often subject to higher requirements than dishes washed manually. For example, even dishes which have been completely cleaned of food residues will not be evaluated as being perfect if, after machine dishwashing, they still have whitish marks based on water hardness or other mineral salts which, due to a lack of wetting agents, originate from dried-on water drops.
In order to obtain sparkling and stain free dishes, rinse aids are therefore nowadays used with success. The addition of rinse aid at the end of the wash program ensures that the water runs off from the ware as completely as possible, so that the various surfaces are residue-free and sparkling at the end of the wash program.
Machine dishwashing in domestic dishwashing machines usually includes a prewash cycle, a main wash cycle and a clear-rinse cycle, which are interrupted by intermediate rinse cycles. With most machines, the prewash cycle for heavily soiled dishes can be selected, but is only chosen by the consumer in exceptional cases, meaning that in most machines a main wash cycle, an intermediate rinse cycle with clean water and a clear-rinse cycle are carried out. The temperature of the main wash cycle varies between 40 and 65° C. depending on the type of machine and program choice. In the clear-rinse cycle, rinse aids are added from a dosing chamber in the machine; these usually comprise nonionic surfactants as the main constituent. Such rinse aids are in liquid form and are described widely in the prior art. Their function is primarily to prevent limescale marks and deposits on the washed dishes.
These so-called “2 in 1” products lead to simplified handling and remove the burden from the consumer of the additional dosing of two different products (detergent and rinse aid). Nevertheless, to operate a domestic dishwashing machine, two dosing operations are periodically required since the regeneration salt must be topped up in the water softening system of the machine after a certain number of wash operations. These water softening systems consist of ion exchanger polymers which soften the hard water flowing into the machine and, after the wash program, are regenerated by rinsing with salt water.
Products which, in the form of so-called “3 in 1” products, combine the conventional detergents, rinse aids and a salt replacement function have recently been described in the prior art. These products are, however, only available as solids (tablets).
The object of the present invention was then to provide a product which is pourable and can thus be readily and freely dosable in terms of amounts and which only has to be dosed once per use without the dosing of another product and thus a duplicate dosing operation being necessary even after a relatively high number of wash cycles. The aim was to provide a liquid to gel-like product which, in addition to the “incorporated rinse aid”, renders it unnecessary to top up the regeneration salt container and thus further simplifies handling. In this connection, the performance of the product was to reach or exceed the level of performance of conventional three-component product dosings (salt-detergent-rinse aid) or of new types of two-component product dosings (“2 in 1” detergent-rinse aids). In this connection, the products to be provided should be superior to conventional products with regard to as many properties as possible. In particular, the dichotomy which arises in the case of many pourable products—advantages with certain properties (flowability, ability to be removed completely, pleasing product appearance etc.) are accompanied by disadvantages with other properties (settling behavior, storage stability, performance etc.)—should be overcome. The object was therefore also to provide products which combine advantageous rheological properties (flowability, ability of the remainder to be removed etc.), advantageous product characteristics (appearance, cleaning power, storage stability etc.) and a production which can be realized industrially without problems and can be carried out in a cost-effective manner.
It has now been found that pourable machine dishwasher products with the abovementioned positive properties can be formulated on the basis of nonaqueous solvents if these products comprise certain polymers containing sulfonic acid groups, and nonionic surfactants,